Calibrating sensor alignment with applied bending moment

ABSTRACT

Examples are disclosed that relate to calibration data related to a determined alignment of sensors on a wearable display device. One example provides a wearable display device comprising a frame, a first sensor and a second sensor, one or more displays, a logic system, and a storage system. The storage system comprises calibration data related to a determined alignment of the sensors with the frame in a bent configuration and instructions executable by the logic system. The instructions are executable to obtain a first sensor data and a second sensor data respectfully from the first and second sensors, determine a distance from the wearable display device to a feature based at least upon the first and second sensor data using the calibration data, obtain a stereo image to display based upon the distance from the wearable display device to the feature, and output the stereo image via the displays.

BACKGROUND

Wearable display devices, such as augmented reality display devices, mayrender virtual content (e.g. holograms) over a view of a real-worldbackground. By presenting separate left-eye and right-eye images fromdifferent perspectives, mixed reality imagery, in which displayedvirtual objects appear to interact with physical objects in thereal-world background, may be presented.

SUMMARY

This Summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This Summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used to limit the scope of the claimed subject matter. Furthermore,the claimed subject matter is not limited to implementations that solveany or all disadvantages noted in any part of this disclosure.

Examples are disclosed that relate to calibrating an alignment ofsensors on a wearable display device. One example provides a wearabledisplay device comprising a frame, a first sensor and a second sensorspatially distributed on the frame, one or more displays supported bythe frame, a logic system, and a storage system. The storage systemcomprises calibration data related to a determined alignment of thefirst sensor and the second sensor with the frame in a bentconfiguration. The storage system further comprises instructionsexecutable by the logic system to obtain first sensor data from thefirst sensor and obtain second sensor data from the second sensor,determine a distance from the wearable display device to a feature basedat least upon the first sensor data and the second sensor data using thecalibration data, obtain a stereo image to display based upon thedistance from the wearable display device to the feature, and output thestereo image via the one or more displays.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an example wearable display device.

FIG. 2 shows a block diagram of an example wearable display device.

FIG. 3 illustrates an example range of human head widths.

FIG. 4A shows an example wearable display device frame in an unbentconfiguration.

FIG. 4B shows the example wearable display device frame in a bentconfiguration illustrative of the device state when worn.

FIG. 5 shows a graph representing an example of pointing error as afunction of bending moment for an example wearable display device.

FIG. 6 shows a graph representing an example of bending moment as afunction of user head width for an example wearable display device.

FIG. 7 shows a flow diagram of an example method for calibrating awearable display device with an applied bending moment.

FIG. 8A and FIG. 8B show a flow diagram of an example method fordisplaying a hologram using calibration data related to a sensoralignment determined with an applied bending moment.

FIG. 9 shows a block diagram of an example computing system.

DETAILED DESCRIPTION

Wearable display devices that display virtual holographic content mayuse sensor data to track a location of the device in an environment. Asan example, a head-mounted display device (HMD) may utilize one or moresensors, such as image sensors and/or inertial motion sensors, to trackhead motion. Direct measurement depth sensors, such as time of flight(ToF) or structured light depth sensors, may be used on some devices forhead tracking. However, such direct measurement sensors may be too largeto fit onto smaller form-factor wearable devices, such as devices havinga form factor of a pair of glasses. Some smaller form-factor HMDs maythus utilize a stereo camera system for head tracking and distancedetermination. A stereo camera system captures images using two (ormore) cameras positioned in a spatially separated arrangement on thedevice to determine distances to objects in the real-world environmentusing triangulation.

Head tracking data determined from such sensors, such as distancesdetermined by head tracking stereo cameras, can be used to displaystereo images that can appear as holograms. This allows the display ofmixed reality images, in which virtual images presented as hologramsappear to co-exist and interact with physical real-world objects andenvironment. However, any errors in determining the distances via sensordata from the sensors can impact a user experience, such as by leadingto an inaccurate rendering or display of the hologram. As a result, ahologram may appear to be displayed at an incorrect or unstablelocation, and/or at an incorrect scale. As examples, an incorrectlylocated hologram may overlap or float above a real-world object uponwhich the hologram is meant to appear as being placed, while an unstablehologram may appear to skip around in location as a user moves withinthe environment. Thus, the inaccurate determination of distance canimpact a mixed reality experience.

As a stereo imaging system determines distance values using a pluralityof cameras arranged at different spatial locations, errors can arise ifthe cameras are misaligned relative to one another compared to anexpected alignment. To avoid such errors, a stereo camera system may becalibrated during a manufacturing process to calibrate an alignment ofthe cameras. The determined calibration can be stored on the device andthen used in the computation of the distance values from the image dataacquired by the cameras.

However, smaller form factor wearable display devices, such as aglasses-like device, may bend when worn, which can impact an alignmentof calibrated sensors on the device. For example, a device with aglasses-like form factor may be designed to be somewhat smaller than anintended head size range so that temple pieces of the device exertpressure against the head of the user. However, the pressure against thehead may result in a bending moment exerted against a frame of thedevice, causing the frame to bend. This bending can cause a misalignmentof sensors positioned on the frame, leading to errors in distancedeterminations that can impact hologram display.

Accordingly, examples are disclosed that relate to calibrating analignment of a first sensor and a second sensor on a wearable displaydevice by performing the calibration with a frame of the device in abent configuration that is representative of the device is worn by auser having a head width within an intended range of head widths.Information regarding the determined alignment of the first sensor andthe second sensor while the frame is in the bent configuration is storedas calibration data. When the wearable display device tracks a locationof the device in an environment, the first sensor obtains first sensordata and the second sensor obtains second sensor data. From the firstsensor data and the second sensor data, the device determines a distancefrom the wearable display device to a feature captured using the sensordata and the calibration data, and obtains a stereo image (comprisingleft and right eye images at different perspectives) for display basedupon the distance determined.

FIG. 1 schematically shows an example wearable display device 100comprising a frame 102, a first camera 104, a second camera 106, adisplay, and temple pieces 108. In this example, the display comprises afirst display 110 and a second display 111 supported by the frame 102,wherein each of the first display 110 and the second display 111 takesthe form of a waveguide configured to deliver a projected image to arespective eye of a user. The first camera 104 and the second camera 106in this example comprise head tracking cameras located respectively atleft and right sides of the frame 102, wherein each of the first cameraand the second camera is located on the frame adjacent to an outer edgeof the frame. A wearable display device may further comprise othersensors that include aligned left and right components. For example,wearable display device 100 includes an eye tracking system comprising afirst eye tracking camera 116 and a second eye tracking camera 118, aface tracking system comprising a first face tracking camera 120 and asecond face tracking camera 122, and a hand tracking system comprising afirst hand tracking camera 124 and a second hand tracking camera 126.Data from the eye tracking system, the face tracking system, and/or thehand tracking system may be used to detect user inputs, and also may beused to help render the stereo image in various examples.

Wearable display device 100 further comprises a first display module 112positioned adjacent to the first camera 104 for displaying a first imageof the stereo image and a second display module 128 positioned adjacentto the second camera 106 for displaying a second image of the stereoimage. Each display module may comprise any suitable display technology,such as a scanned beam projector, a microLED (light emitting diode)panel, a microOLED (organic light emitting diode) panel, or a LCoS(liquid crystal on silicon) panel, as examples. Further, various optics,such as the above-mentioned waveguides, one or more lenses, prisms,and/or other optical elements may be used to deliver displayed images toa user's eyes.

In addition to cameras, a wearable display device further may includeother types of sensors sensitive to misalignment due to bending. Forexample, wearable display device 100 comprises an inertial measurementunit system (IMU) comprising a first IMU 114 positioned adjacent to thefirst display module 112 and a second IMU 130 positioned adjacent to thesecond display module 128. First camera 104, first display module 112,and first IMU 114 may be closely mechanically coupled to help preventchanges in alignment from occurring between the first camera 104, thefirst display module 112, and the first IMU 114. Second camera 106,second display module 128, and second IMU 130 may be similarly closelymechanically coupled. IMU data can be used to adjust a displayed imagebased upon head motion. IMUs 114 and 130 also can be calibrated with abending moment applied to the wearable display device 100.

FIG. 2 shows a block diagram of an example wearable display device 200.Wearable display device 100 of FIG. 1 is an example of display device200 of FIG. 2 . Wearable display device 200 comprises a head trackingsubsystem 202 comprising a first head tracking camera 204 and a secondhead tracking camera 206, a display subsystem 236, and a controller 242comprising a logic subsystem 238 and a storage subsystem 240, examplesof which are discussed in more detail in FIG. 9 . The display subsystem236 in the depicted example comprises a first display module 232 and asecond display module 234, wherein the first display module isconfigured to display an image for delivery to a first eye of a user andthe second display module is configured to display an image for deliveryto a second eye of a user as part of a stereo image. In other examples,a display subsystem may have a single display configured to displayimages to both eyes.

As mentioned above, a displayed stereo image can be rendered based uponhead tracking data captured by the head tracking subsystem 202. The headtracking data can be used to determine a location of the device in anenvironment and a distance from the device to objects in theenvironment. This data can then be used to determine left-eye andright-eye images to display that place the hologram in an intendedposition (e.g. on top of a table or on a wall). An optional inertialmeasurement unit (IMU) subsystem 226 comprising a first IMU 228 and asecond IMU 230 may be used in combination with the head trackingsubsystem 202 to help determine the location of the device in theenvironment, such as by tracking head movement. Other sensor data thatmay be used to render the stereo image data include eye tracking datafrom an optional eye tracking system 208 comprising a first eye trackingcamera 210 and a second eye tracking camera 212, face tracking data froman optional face tracking subsystem 214 comprising a first face trackingcamera 216 and a second face tracking camera 218, and hand tracking datafrom an optional hand tracking subsystem 220 comprising a first handtracking camera 222 and a second hand tracking camera 224. Eye trackingdata from the eye tracking subsystem 208 may be used to determine a gazedirection, which can be used to place a hologram in an environmentand/or for detecting eye gesture inputs for interacting with thehologram. Face tracking data from the face tracking subsystem 214 andhand tracking data from the hand tracking subsystem 220 may be used asface gesture inputs and hand gesture inputs, respectively, to interactwith the hologram. Misalignment of any of the eye tracking cameras, theface tracking cameras, or the hand tracking cameras may result ininaccurate hologram placement and/or inaccurate or mistaken inputgestures.

As mentioned above, a wearable display device with a glasses form factormay be designed to be somewhat smaller than an intended head size rangeso that temple pieces of the device exert pressure against the head ofthe user, causing the frame to bend. The bending may be different fordifferent users, as a wearable display device may be used by apopulation of users with a distribution of different head widths. FIG. 3illustrates a human head, 300, and qualitatively shows a range of headwidths extending between a minimum head width 302 to a maximum headwidth 304 of an intended range of head widths for a wearable device. Tohelp ensure that a wearable display device securely fits even thesmallest head widths in the intended range of head widths, the wearabledisplay device may be designed such that the temple pieces exertpressure against heads of a smallest size within the intended range. Assuch, a frame of the device may bend somewhat for users with thesmallest head widths in the intended range, and more for users withlarger head widths.

FIG. 4A shows at 400A an example wearable display device frame 402 in anunbent configuration with no applied bending moment, such as in theas-built state of the wearable display device. In contrast, FIG. 4Bshows, at 400B, the frame 402 in a bent configuration such as under abending moment illustrative of the device being worn by a user. Analignment between a first camera 404 and a second camera 406 of a headtracking system is represented by arc 408A. Bending of the frame 402that occurs when the wearable display device is worn by the user changesan alignment of the first and second cameras, as indicated by thegreater curvature of arc 408B compared to arc 408A. Where the alignmentof the first camera 404 and the second camera 406 is calibrated in thedevice state shown at 400A, the bend shown at arc 408B can inducepointing errors, wherein the term “pointing error” indicates an error inthe alignment of a sensor (e.g. a camera, IMU, and/or other calibratedsensor) compared to a calibrated alignment. A pointing error above athreshold value may visibly impact a displayed hologram.

FIG. 5 shows a graph 500 that qualitatively illustrates an examplelinear relationship between pointing error and bending moment applied toan example wearable display device. A pointing error over a thresholdvalue 502 may impact a user experience, as displayed holograms mayappear misplaced. However, a bending moment that gives rise to apointing error over the threshold may be met by a substantial portion ofa range of intended head sizes where the camera alignment is calibratedin an unbent configuration such as with no bending moment applied.

FIG. 6 shows a graph 600 qualitatively representing an example linearrelationship between bending moment and user head width for a wearabledisplay device such as those described herein. As mentioned above, awearable display device may be designed to accommodate a selected rangeof head widths. An example of such a range is shown by locations 602 and604 in FIG. 6 . The vertical axis illustrates a range of bending momentsthat corresponds to this range of head sizes. Head width 602 representsa minimum head width within the intended range of head widths, and 604indicates a maximum head width. The bending moment shown at 606corresponds to a determined moment that provides a suitably secure fiton a head of the minimum width in the range of intended head widths, andbending moment 608 represents a bending moment corresponding to amaximum head width within the range of intended head widths. Thus,sensor alignment on the wearable display device can be calibrated in abent configuration corresponding to a bending moment resulting from ahead width within the intended range is applied. An example of such abending moment is shown at midpoint 610. Calibrating sensor alignmentmidway between the minimum and maximum intended head widths mayaccommodate both the minimum and maximum head widths with acceptablepointing error. In other examples, a bent configuration corresponding toa head width other than a midpoint width can be used for calibration,such as a minimum head width, a median head with, or other head widthbased on a statistical user population study.

FIG. 7 illustrates a flow diagram depicting example method 700 forcalibrating an alignment of a first sensor and a second sensor of awearable display device. Method 700 may be performed on wearable displaydevices shown in FIG. 1 , FIG. 2 , FIG. 4 , and/or any other suitablewearable display device. Method 700 comprises, at 702, applying bendinga frame of a wearable display device to place the frame in a bentconfiguration. The bent configuration may be selected based upon a rangeof intended head widths, and application of the bent configurationcauses the bending of a frame of the device, thereby changing analignment of sensors on the frame compared to an unbent device state. Insome examples, the bent configuration may correspond to a head widthwithin an intended range of head widths, as indicated at 704.

Continuing, method 700 further comprises, at 706, determining analignment of a first sensor and a second sensor at the bentconfiguration. The alignment determined may comprise one or more of analignment of a first head tracking camera and a second head trackingcamera at 708, an alignment of a first eye tracking camera and a secondeye tracking camera at 710, an alignment of a first facing trackingcamera and a second face tracking camera at 712, an alignment of a firsthand tracking camera and a second hand tracking camera at 714, and analignment of a first IMU and a second IMU at 716. Further, alignmentsbetween sensors of different types also may be determined, such as analignment between a camera and an IMU. Method 700 further comprises, at718, storing calibration data related to the alignment of the first andsecond sensors in memory on the wearable display device. The calibrationdata may comprise one or more datum related to the alignment of anysuitable sensors.

FIG. 8 shows a flow diagram depicting example method 800 for usingcalibration data to output a stereo image for display via a wearabledisplay device. Method 800 may be performed on any suitable wearabledisplay device, such as those shown in FIG. 1 , FIG. 2 , and/or FIG. 4and described herein. Method 800 comprises, at 802, obtaining a firstimage from a first head tracking camera and obtaining a second imagefrom a second head tracking camera. The device further may comprise eyetracking cameras 806, face tracking cameras 808, and face trackingcameras 810. Method 800 may further comprise, at 812, obtaining motiondata from a first IMU and a second IMU.

At 814, method 800 further comprises using calibration data related to adetermined alignment of the first and second cameras in a bentconfiguration to determining a distance from the wearable display deviceto a feature captured in the first and second images. The calibrationdata comprises calibrations of an alignment of the cameras when thedevice is in the bent configuration, and the bent configuration maycorrespond to a bent configuration that would result from the devicebeing worn on a head. In some examples, at 816, the bent configurationcorresponds to a head width within an intended range of head widths. Inother examples, the bent configuration may correspond to a minimum headwidth in the intended range of head widths.

Method 800 further comprises adjusting image data from the head trackingcameras using the calibration data, as indicated at 818. Further, method800 further may comprise one or more of using the calibration data toadjust eye tracking data at 820, using calibration data to adjust facingtracking data at 822, using calibration data to adjust hand trackingdata at 824, or using calibration data to adjust IMU data from the firstand second IMUs at 826. Any other suitable data from sensors on thewearable display device also may be adjusted using the calibration data.Using the calibration data acquired with a bent configuration applied toa frame to adjust the head tracking data may reduce a pointing errorcompared to adjusting the head tracking data using calibration dataacquired without a bent configuration applied to the frame.

At 828, method 800 further comprises obtaining a stereo image fordisplay, the stereo image determined based upon the distance from thewearable display device to the feature imaged based on the head trackingdata. The stereo image may be rendered locally on the wearable displaydevice, or rendered by and obtained from a remote service based upondata provided by the display device to the remote service (e.g. wherethe virtual content corresponds to an online game, game content may berendered remotely by a remote game service and sent to the wearabledisplay device based upon head tracking data and/or other suitable dataprovided to the remote game service). Additionally or alternatively, thestereo image displayed may be further based on one or more of eyetracking data at 832, face tracking data at 834, hand tracking data at836, and IMU data at 838. At 840, method 800 further comprisesoutputting the stereo image to one or more displays on the wearabledisplay device.

In some embodiments, the methods and processes described herein may betied to a computing system of one or more computing devices. Inparticular, such methods and processes may be implemented as acomputer-application program or service, an application-programminginterface (API), a library, and/or other computer-program product.

FIG. 9 schematically shows a non-limiting embodiment of a computingsystem 900 that can enact one or more of the methods and processesdescribed above. Computing system 900 is shown in simplified form.Computing system 900 may take the form of one or more personalcomputers, server computers, tablet computers, home-entertainmentcomputers, network computing devices, gaming devices, mobile computingdevices, mobile communication devices (e.g., smart phone), and/or othercomputing devices.

Computing system 900 includes a logic subsystem 902 and a storagesubsystem 904. Computing system 900 may optionally include a displaysubsystem 906, input subsystem 908, communication subsystem 910, and/orother components not shown in FIG. 9 .

Logic subsystem 902 includes one or more physical devices configured toexecute instructions. For example, the logic machine may be configuredto execute instructions that are part of one or more applications,services, programs, routines, libraries, objects, components, datastructures, or other logical constructs. Such instructions may beimplemented to perform a task, implement a data type, transform thestate of one or more components, achieve a technical effect, orotherwise arrive at a desired result.

The logic machine may include one or more processors configured toexecute software instructions. Additionally or alternatively, the logicmachine may include one or more hardware or firmware logic machinesconfigured to execute hardware or firmware instructions. Processors ofthe logic machine may be single-core or multi-core, and the instructionsexecuted thereon may be configured for sequential, parallel, and/ordistributed processing. Individual components of the logic machineoptionally may be distributed among two or more separate devices, whichmay be remotely located and/or configured for coordinated processing.Aspects of the logic machine may be virtualized and executed by remotelyaccessible, networked computing devices configured in a cloud-computingconfiguration.

Storage subsystem 904 includes one or more physical devices configuredto hold instructions executable by the logic machine to implement themethods and processes described herein. When such methods and processesare implemented, the state of storage subsystem 904 may betransformed—e.g., to hold different data.

Storage subsystem 904 may include removable and/or built-in devices.Storage subsystem 904 may include optical memory (e.g., CD, DVD, HD-DVD,Blu-Ray Disc, etc.), semiconductor memory (e.g., RAM, EPROM, EEPROM,etc.), and/or magnetic memory (e.g., hard-disk drive, floppy-disk drive,tape drive, MRAM, etc.), among others. Storage subsystem 904 may includevolatile, nonvolatile, dynamic, static, read/write, read-only,random-access, sequential-access, location-addressable,file-addressable, and/or content-addressable devices.

It will be appreciated that storage subsystem 904 includes one or morephysical devices. However, aspects of the instructions described hereinalternatively may be propagated by a communication medium (e.g., anelectromagnetic signal, an optical signal, etc.) that is not held by aphysical device for a finite duration.

Aspects of logic subsystem 902 and storage subsystem 904 may beintegrated together into one or more hardware-logic components. Suchhardware-logic components may include field-programmable gate arrays(FPGAs), program- and application-specific integrated circuits(PASIC/ASICs), program- and application-specific standard products(PSSP/ASSPs), system-on-a-chip (SOC), and complex programmable logicdevices (CPLDs), for example.

It will be appreciated that a “service”, as used herein, is anapplication program executable across multiple user sessions. A servicemay be available to one or more system components, programs, and/orother services. In some implementations, a service may run on one ormore server-computing devices.

When included, display subsystem 906 may be used to present a visualrepresentation of data held by storage subsystem 904. This visualrepresentation may take the form of a graphical user interface (GUI). Asthe herein described methods and processes change the data held by thestorage machine, and thus transform the state of the storage machine,the state of display subsystem 906 may likewise be transformed tovisually represent changes in the underlying data. Display subsystem 906may include one or more display devices utilizing virtually any type oftechnology. Such display devices may be combined with logic subsystem902 and/or storage subsystem 904 in a shared enclosure, or such displaydevices may be peripheral display devices.

When included, input subsystem 908 may comprise or interface with one ormore user-input devices such as a keyboard, mouse, touch screen, or gamecontroller. In some embodiments, the input subsystem may comprise orinterface with selected natural user input (NUI) componentry. Suchcomponentry may be integrated or peripheral, and the transduction and/orprocessing of input actions may be handled on- or off-board. Example NUIcomponentry may include a microphone for speech and/or voicerecognition; an infrared, color, stereoscopic, and/or depth camera formachine vision and/or gesture recognition; a head tracker, eye tracker,accelerometer, and/or gyroscope for motion detection and/or intentrecognition; as well as electric-field sensing componentry for assessingbrain activity.

When included, communication subsystem 910 may be configured tocommunicatively couple computing system 900 with one or more othercomputing devices. Communication subsystem 910 may include wired and/orwireless communication devices compatible with one or more differentcommunication protocols. As non-limiting examples, the communicationsubsystem may be configured for communication via a wireless telephonenetwork, or a wired or wireless local- or wide-area network. In someembodiments, the communication subsystem may allow computing system 900to send and/or receive messages to and/or from other devices via anetwork such as the Internet.

Another example provides a wearable display device comprising a frame, afirst sensor and a second sensor spatially distributed on the frame, oneor more displays supported by the frame, a logic system, a storagesystem comprising calibration data related to a determined alignment ofthe first sensor and the second sensor with the frame in a bentconfiguration, and instructions executable by the logic system. Theinstructions executable to obtain a first sensor data from the firstcamera, and obtain a second sensor data from the second camera, usingthe calibration data, determine a distance from the wearable displaydevice to a feature based at least upon the first sensor data and thesecond sensor data, obtain a stereo image to display based upon thedistance from the wearable display device to the feature, output thestereo image via the one or more displays. Alternately or additionallyeach of the first sensor and the second sensor are located on the frameadjacent to an outer edge of the frame. Alternatively or additionally,the first sensor and the second sensor comprise head tracking cameras.The device alternatively or additionally comprising a first displaymodule positioned adjacent to the first camera for displaying a firstimage of the stereo image, and a second display module positionedadjacent to the second camera for displaying a second image of thestereo image. The device alternatively or additionally comprising one ormore of an inertial measurement unit (IMU) system comprising a first IMUpositioned adjacent to the first display module and a second IMUpositioned adjacent to the second display module, an eye tracking systemcomprising a first eye tracking camera and a second eye tracking camera,a face tracking system comprising a first face tracking camera and asecond face tracking camera, or a hand tracking system comprising afirst hand tracking camera and a second hand tracking camera, andwherein the instructions are executable to adjust data from the one ormore of the IMU system, the eye tracking system, the face trackingsystem, or the hand tracking system using the calibration data.Alternatively or additionally, the bent configuration is based on anintended range of head widths.

Another example provides on a wearable display device comprising aframe, a first sensor and a second sensor spatially distributed on theframe, and one or more displays supported by the frame, a method ofcalibrating an alignment of the first sensor and the second sensor. Themethod comprising applying a bent configuration to the frame,determining a determined alignment of the first sensor and the secondsensor in the bent configuration, storing calibration data in memory onthe wearable display device based upon the determined alignment.Applying the bent configuration alternatively or additionally comprisesapplying a bent configuration selected within an intended range of headwidths. Alternatively or additionally, the first sensor and the secondsensor respectively comprise a first head tracking camera and a secondhead tracking camera. Alternatively or additionally, the first sensorand the second sensor respectively comprise a first eye tracking cameraand a second eye tracking camera. Alternatively or additionally, thefirst sensor and the second sensor respectively comprise a first facetracking camera and a second face tracking camera. Alternatively oradditionally, the first sensor and the second sensor respectivelycomprise a first hand tracking camera and a second hand tracking camera.Alternatively or additionally, the first sensor and the second sensorrespectively comprise a first inertial measurement unit (IMU) and asecond IMU.

Another example provides on a wearable display device comprising aframe, a first camera and a second camera spatially distributed on theframe, one or more displays supported by the frame, and a storage systemcomprising calibration data related to a determined alignment of thefirst camera and the second camera with the frame in a bentconfiguration, a method comprising obtaining a first image of anenvironment from the first camera and obtaining a second image of theenvironment from the second camera, using the calibration data,determining a distance from the wearable display device to a featurecaptured in the first image and the second image, obtaining a stereoimage to display based upon the distance from the wearable displaydevice to the feature, outputting the stereo image via the one or moredisplays. Alternatively or additionally, the first camera and the secondcamera comprise head tracking cameras. Alternatingly or additionally,the wearable display device further comprises an eye tracking systemcomprising a first eye tracking camera and a second eye tracking camera,and the method further comprising adjusting eye tracking data determinedby the eye tracking system based upon the calibration data.Alternatively or additionally, the wearable display device furthercomprises a face tracking system comprising a first face tracking cameraand a second face tracking camera, and the method further comprisingadjusting face tracking data determined by the face tracking systembased upon the calibration data. Alternatively or additionally, thewearable display device further comprises a hand tracking systemcomprising a first hand tracking camera and a second hand trackingcamera, and the method further comprising adjusting hand tracking datadetermined by the hand tracking system based upon the calibration data.Alternatively or additionally, the wearable display device furthercomprises a first inertial measurement unit (IMU) and a second IMU, andthe method further comprising adjusting IMU data determined by the firstand second IMU based upon the calibration data. Alternately oradditionally the bent configuration is based within an intended range ofhead widths.

It will be understood that the configurations and/or approachesdescribed herein are exemplary in nature, and that these specificembodiments or examples are not to be considered in a limiting sense,because numerous variations are possible. The specific routines ormethods described herein may represent one or more of any number ofprocessing strategies. As such, various acts illustrated and/ordescribed may be performed in the sequence illustrated and/or described,in other sequences, in parallel, or omitted. Likewise, the order of theabove-described processes may be changed.

The subject matter of the present disclosure includes all novel andnon-obvious combinations and sub-combinations of the various processes,systems and configurations, and other features, functions, acts, and/orproperties disclosed herein, as well as any and all equivalents thereof.

1. A wearable display device comprising: a frame; a first sensor and asecond sensor spatially distributed on the frame; one or more displayssupported by the frame; a logic system; and a storage system comprisingcalibration data related to a determined alignment of the first sensorand the second sensor with the frame in a bent configuration, andinstructions executable by the logic system to obtain first sensor datafrom the first sensor, and obtain second sensor data from the secondsensor, using the calibration data, determine a distance from thewearable display device to a feature based at least upon the firstsensor data and the second sensor data; obtain a stereo image to displaybased upon the distance from the wearable display device to the feature;and output the stereo image via the one or more displays.
 2. The deviceof claim 1, wherein the first sensor comprises a camera and the secondsensor comprises an inertial measurement unit (IMU).
 3. The device ofclaim 1, wherein the first sensor and the second sensor comprise headtracking cameras.
 4. The device of claim 3, further comprising a firstdisplay module positioned adjacent to the first camera for displaying afirst image of the stereo image, and a second display module positionedadjacent to the second camera for displaying a second image of thestereo image.
 5. The device of claim 4, further comprising one or moreof an inertial measurement unit (IMU) system comprising a first IMUpositioned adjacent to the first display module and a second IMUpositioned adjacent to the second display module, an eye tracking systemcomprising a first eye tracking camera and a second eye tracking camera,a face tracking system comprising a first face tracking camera and asecond face tracking camera, or a hand tracking system comprising afirst hand tracking camera and a second hand tracking camera, andwherein the instructions are executable to adjust data from the one ormore of the IMU system, the eye tracking system, the face trackingsystem, or the hand tracking system using the calibration data.
 6. Thedevice of claim 1, wherein the bent configuration is based on anintended range of head widths.
 7. On a wearable display devicecomprising a frame, a first sensor and a second sensor spatiallydistributed on the frame, and one or more displays supported by theframe, a method of calibrating an alignment of the first sensor and thesecond sensor, the method comprising: bending the frame to place theframe in a bent configuration to the frame; determining a determinedalignment of the first sensor and the second sensor in the bentconfiguration; and storing calibration data in memory on the wearabledisplay device based upon the determined alignment.
 8. The method ofclaim 7, wherein the bent configuration is based upon an intended rangeof head widths.
 9. The method of claim 7, wherein the first sensor andthe second sensor respectively comprise a first head tracking camera anda second head tracking camera.
 10. The method of claim 7, wherein thefirst sensor and the second sensor respectively comprise a first eyetracking camera and a second eye tracking camera.
 11. The method ofclaim 7, wherein the first sensor and the second sensor respectivelycomprise a first face tracking camera and a second face tracking camera.12. The method of claim 7, wherein the first sensor and the secondsensor respectively comprise a first hand tracking camera and a secondhand tracking camera.
 13. The method of claim 7, wherein the firstsensor and the second sensor respectively comprise a first inertialmeasurement unit (IMU) and a second IMU.
 14. On a wearable displaydevice comprising a frame, a first camera and a second camera spatiallydistributed on the frame, one or more displays supported by the frame,and a storage system comprising calibration data related to a determinedalignment of the first camera and the second camera with the frame in abent configuration, a method comprising: obtaining a first image of anenvironment from the first camera and obtaining a second image of theenvironment from the second camera; using the calibration data,determining a distance from the wearable display device to a featurecaptured in the first image and the second image; obtaining a stereoimage to display based upon the distance from the wearable displaydevice to the feature; and outputting the stereo image via the one ormore displays.
 15. The method of claim 14, where the first camera andthe second camera comprise head tracking cameras.
 16. The method ofclaim 15, wherein the wearable display device further comprises an eyetracking system comprising a first eye tracking camera and a second eyetracking camera, and the method further comprising adjusting eyetracking data determined by the eye tracking system based upon thecalibration data.
 17. The method of claim 15, wherein the wearabledisplay device further comprises a face tracking system comprising afirst face tracking camera and a second face tracking camera, and themethod further comprising adjusting face tracking data determined by theface tracking system based upon the calibration data.
 18. The method ofclaim 15, wherein the wearable display device further comprises a handtracking system comprising a first hand tracking camera and a secondhand tracking camera, and the method further comprising adjusting handtracking data determined by the hand tracking system based upon thecalibration data.
 19. The method of claim 14, wherein the wearabledisplay device further comprises a first inertial measurement unit (IMU)and a second IMU, and the method further comprising adjusting IMU datadetermined by the first and second IMU based upon the calibration data.20. The method of claim 14, wherein the bent configuration is based uponan intended range of head widths.